Everyone in the house is very orderly and precise about when everything gets done ultimately showing order is a key part of the family dynamic. Bradbury does this to show everything is routine and important to the family itself.
We see order again through “Nine fifteen, time to clean” showing everything that needs to be done gets done at a set time and in an orderly fashion.
Without the sense of order and structure within the family the relationship between one another would be much more distant. Order is the key asset in the dynamic of the family throughout the passage.